Aphasia is a stroke-related disability of language processing that affects about one million people in the United States. Human activity is so dependent on spoken communication that impairments of spoken language processing, such as aphasia, can be devastating. In addition to functional impairments such as inability to work, language impairments can also cause social isolation and its consequent negative outcomes on mental and physical health. Because language processing calls on many different cognitive faculties, aphasia may have many different underlying causes and each aphasic individual may have a subtly different impairment. Designing effective rehabilitation strategies depends on our understanding of the nature of the impairment, thus, the focus of this proposal is on using behavioral experiments and computational modeling methods to develop a formal theory of aphasic spoken word comprehension. The proposed experiments will investigate phonological, semantic, and cognitive control aspects of word processing in a large and diverse set of aphasic individuals and unimpaired control participants using behavioral and eye tracking measures. These measures will provide new insights into the dynamics of word processing in aphasia. Computational modeling will be used to develop and test formal accounts of word processing deficits in aphasia. With a better understanding of the underlying causes of aphasic language impairments and a formal model of aphasia, more effective rehabilitation strategies can be developed. PUBLIC HEALTH RELEVANCE: This project will apply innovative behavioral, eye-tracking, and computational modeling techniques to better understand word processing in aphasic patients. The investigations are likely to contribute substantially to the understanding of language impairments in aphasia and to the development of novel rehabilitation strategies for aphasia.